The invention relates to a device for feeding a work to a tool such as cutting area of the wire saw, and more particularly to such device comprising an air float in a water vessel of which buoyancy is utilized for pushing the work to the tool as the working such as cutting proceeds with controlled pushing force.
In some machine tools such as the wire saw, not the tool but the work is fed toward the tool. When pushing the work to a wire or an array consisting of a number of parallelly arranged wires extended in tension is alternatingly moved in longitudinal direction with supplying abrasive medium, the work pushed thereagainst is cut. If a table supporting the work thereon is fed too slowly in comparison with the cutting rate, the cutting force is to be too small to attain efficient cutting. In order to attain efficient cutting with keeping fineness and accuracy of the cutting of the work, it is very important to control such feeding rate and consequently such cutting force or pushing force, in addition to other working conditions such as wire reciprocal movement speed, wire tension, amount of abrasive medium to be supplied, pace for delivering out fresh wires to relieve worn and fatiqued wires and so on.
Hitherto a hydraulic piston-cylinder device has been used for feeding the work which is fixed on the table mounted at the free end of the piston. Having set various working conditions as referred to above, the operator manually handle the device to supply oil under pressure into the cylinder to push said table and consequently the work against the wire array and controll the oil supply rate with watching cutting progress so as to attain desired feeding rate or pushing force.
The hydraulic device has inevitably seal means such as piston ring between the piston outersurface and the cylinder inner surface so that there is caused friction. Such friction often hinders smooth and stable feeding and retraction of the work which may jeopardize fineness and accuracy of the cutting or further give damages thereto.
In order to overcome the defect of the piston-cylinder feeding device, e.g. JP-B-2794/1983 proposes a device comprising a cylindrical float having an open bottom to be buoyed in a water vessel and a work table mounted on the top thereof; a cylindrical chamber having an open top and arranged stationarily in said vertically movable float; and means for controllably supplying oil under pressure into said chamber at the bottom thereof so as to control the pressure of air confined in said float depending on varied oil level in said chamber.
According to this float-type device the table and consequently the work is raised up against the wire array by manually controlling oil supply rate like as in said piston-cylinder device but smoothly and stably different therefrom. This is, however, still unsatisfactory in that the device is to be too bulky and complex as a whole and consequently expensive due to the hydraulic pressure system.